Show how delegate definition matters, the following sample will rightfully not compile

Delegates.cs

 class Program
   {
      delegate bool delA(string item);
      delegate bool delB(string item);

      static void Main(string[] args)
      {
         delA del = s => true;
         callA(del);
         callB(del);
      }
      static void callA(delA a)
      {
      }
      static void callB(delB b)
      {
      }

   }